Machine for making metal tubes

ABSTRACT

A SERIES OF DRIVE ROLLERS ARE PROVIDED TO FEED A METAL STRIP ALONG A HELICAL PATH AROUND A ROTATING MANDREL. THE STRIP HAS AN UPSTANDING LONGITUDINAL FLANGE ALONG ONE EDGE THEREOF AND A U-SHAPED LONGITUDINAL FLANGE ALONG THE OTHER EDGE, ADAPTED TO INTERLOCK WITH THE UPSTANDING FLANGE. THE STRIP IS ALSO FORMED WITH AN INTERMEDIATE LONGITUDINAL CONVOLUTION SO THAT THE TUBE WILL BE FLEXIBLE. THE DRIVE ROLLERS ARE DRIVEN AT A SURFACE SPEED GREATER THAN THAT OF THE MANDREL AND ARE ANGLED IN ACCORDANCE WITH THE HELICAL PITCH ANGLE OF THE STRIP. A STATIONARY MEMBER WITH A HELICAL SURFACE IS DISPOSED AROUND THE MANDREL TO GUIDE THE EDGE OF THE STRIP. THE FLANGES ARE INTERLOCKED AND THEN BENT INWARDLY AT AN ANGLE BETWEEN A THIN CONICAL ROLLER AND ONE OF THE DRIVE ROLLERS WHICH HAS A FRUSTO-CONICAL SURFACE. THE BENT FLANGES ARE FLATTENED BY A ROLLER WHICH IS ANGLED MORE SHARPLY THAN THE DRIVE ROLLERS.

Sept. 21, 1971 PARMA 3,606,779

MACHINE FOR MAKING METAL TUBES v Filed Feb. 24, 1969 2 Sheets-Sheet 1 N VEN T01? Domenico Par/11a g ,Q M 4 W,

Sept. 21, 19-71 D, PARMA 3,606,779

I MACHINE FOR MAKING METAL TUBES Filed Febf24, 1969 f2 Sheets-Shah: 2

3,606,779 MACHINE FOR MAKING METAL TUBES Domenico Parma, Apartado Aereo 14600, Bogota, Colombia Filed Feb. 24, 1969, Ser. No. 801,551

Int. Cl. B21c 37/12 U.S. Cl. 72-49 2 Claims ABSTRACT OF THE DISCLOSURE A series of drive rollers are provided to feed a metal strip along a helical path around a rotating mandrel. The strip has an upstanding longitudinal flange along one edge thereof and a U-shaped longitudinal flange along the other edge, adapted to interlock with the upstanding flange. The strip is also formed with an intermediate longitudlnal convolution so that the tube will be flexible. The drive rollers are driven at a surface speed greater than that of the mandrel and are angled in accordance with the helical pitch angle of the strip. A stationary member with a helical surface is disposed around the mandrel to guide the edge of the strip. The flanges are interlocked and then bent inwardly at an angle between a thin conical roller and one of the drive rollers which has a frusto-conical surface. The bent flanges are flattened by a roller which is angled more sharply than the drive rollers.

This invention relates to a machine for making a metal tube by helically coiling a metal strip and forming a continuous helical joint between the edges of the adjacent coils. The tube is preferably of the flexible type. Flexibility may be imparted to the tube by providing convolutions therein. i

The tube making machine of the present invention preferably utilizes a metal strip having an upstanding longitudinal flange extending along one edge and a channcl shaped longitudinal flange extending along the other edge. The strip also preferably comprises one or more longitudinal convolutions, so that the finished tube will be flexible. The tube is made by coiling the strip, so that the channel shaped flange of each coil is interlocked with the upstanding flange of the preceding coil.

One object of the present invention is to provide a tube making machine having new and improved means for bending and flattening the interlocked flanges, so as to provide a tight and rigid joint between the adjacent coils.

Accordingly, the present invention preferably comprises a rotary mandrel around which the strip is coiled. The strip is propelled by a plurality of drive rollers, one of which is formed with an angularly extending annular surface for bending the inboard leg of the channel shaped flange in an outboard direction. A thin tapering wheel acts in opposition to such annular surface and is effective to bend the outboard leg of the channel shaped flange in an inboard direction. Of course, the upstanding flange is captive between the inboard and outboard legs and is bent along with the inboard leg.

The partially bent flanges are preferably flattened by another roller which is canted or skewed at a considerable angle, relative to the mandrel. The drive rollers are preferably skewed at an angle corresponding to the pitch angle of the coiled strip.

Another object is to provide a tube making machine in which the tube is enabled to slide freely along the mandrel as the strip is coiled.

Accordingly, the drive rollers are preferably driven at a surface speed substantially greater than the surface speed of the mandrel, so as to produce a loose fit between the tube and the mandrel. The flattening roller is also preferably driven at a greater surface speed than that of the mandrel.

United States Patent "Ice Patented Sept. 21, 1971 Further objects, advantages and features of the present invention will appear from the following description, taken with the accompanying drawings, in which:

FIG. 1 is a somewhat diagrammatic perspective view of a tube making machine to be described as an illustrative embodiment of the present invention.

FIG. 2 is a sectional perspective of the metal strip which is coiled into a tube by the machine of FIG. 1.

FIG. 3 is a sectional view showing the finished tube.

FIG. 4 is a somewhat diagrammatic plan view of the machine.

FIG. 5 is a vertical section, taken generally along the line 55 in FIG. 4.

FIG. 6 is a horizontal section, taken generally along the line 66 in FIG. 5.

It will be seen that FIG. 1 illustrates a machine 10 adapted to make a metal tube 12 by helically coiling a metal strip 14. As shown to best advantage in FIG. 2, the strip 14 preferably is formed with an upstanding longitudinal flange 16 extending along one edge of the strip. A channel shaped longitudinal flange 18 extends along the other edge of the strip 14. The flange 18 comprises inboard and outboard legs 20 and 22. The inboard leg 20 is bent upwardly from the strip 14, while the outboard leg 22 is bent downwardly from the inboard leg 20. The illustrated flange 18 is generally U-shaped in cross section.

In order that the finished metal tube 12 may be flexible, the strip 14 is formed with at least one longitudinal convolution 24 which is illustrated as being generally V-shaped in cross section. When the strip 14 has been helically coiled to form the tube 12, the convolution 24 extends helically along the entire length of the tube so as to impart flexibility to the tube. When the tube 12 is flexed, the convolution 24 is compressed on one side of the tube and spread wider on the opposite side thereof.

The illustrated machine 10 comprises a rotary mandrel or shaft 26 which is continuously rotated by a drive mechanism 28, as indicated diagrammatically in FIG. 4. A suitable connection 30 is provided between the drive mechanism 28 and the mandrel 26. It will be understood that the drive mechanism 28 comprises a source of motive power and various gears, shafts, couplings and the like. Those skilled in the art will be familiar with such drive mechanisms.

employed. However, the number and arrangement of the drive rollers may be varied. The illustrated rollers 32-38 are distributed around the periphery of the mandrel 26 at angular intervals. Moreover, the rollers are staggered along the helical path of the strip 14. Preferably, the rollers 32, 34, 36 and 38 are all driven by the drive mechanism 28. For this purpose, driving connections 42, 44, 4 6 and 48 are provided between the drive mechanism 28 and the rollers 32-38.

Each of the rollers 32-38 is preferably formed with a cylindrical outer surface 50 for engaging and propelling the strip 14. The surface 50 is illustrated as being striated, knurled or otherwise roughened to provide a secure frictional engagement between the roller and the strip 14. Each of the rollers 3238 is preferably formed with a circumferential groove 52, extending along the cylindrical drive surface 50, to receive the convolution 26. The engagement between the convolution 26 and the groove 52 assists in maintaining the strip 14 in lateral alignment with the successive rollers 32-38.

To provide further assistance in the helical coiling of the strip 14, a stationary guide 54 is arranged to extend around the mandrel 26, at the point where the strip 14 is fed to the mandrel. The guide 54 is generally cylindrical in shape and is formed with a helical guide surface 56 extending around one end of the guide. The surface 56 is adapted to guide the upstanding flange 16 along a helical path as the strip is coiled around the mandrel 26.

As shown to best advantage in FIGS. 1, and 6, the

strip 14 is helically coiled so that the channel shaped flange l18 of each coil is interlocked with the upstanding flange 16 of the adjacent coils. Thus, the upstanding flange 16 is held captive between the legs 20 and 22 of the channel shape flange 18.

The tube making machine is provided with means for bending and then flattening the flanges 16 and 18 so as to form a rigid helical joint between the adjacent coils of the strip 14. Preferably, the flanges 16 and 18 are given an initial bend, and then are flattened.

The initial bending of the flanges 16 and 18 is shown to best advantage in FIGS. 5 and 6. It will be seen that the drive roller 38 is formed 'with an angularly extending annular surface 58 which engages the inboard leg 20 of the flange 18 and bends the inboard leg in an outboard direction. The illustrated annular bending surface 58 is frusto-conical in shape.

A thin, tapering roller or wheel 60 is provided to act in opposition to the angular bending surface 58 on the roller 38. The wheel 50 engages the outboard leg 22 of the flange 18 and causes the outboard leg to be bent in an inboard direction. It will be seen that the wheel 60 tapers in thickness between its center and its outer edge. The wheel 60 has a pair of surfaces 62 which are generally frusto-conical in shape. The wheel 60 is thin enough and tapered sufliciently to allow the thin edge portion of the wheel to enter the groove or channel 64 between the partially bent flanges '16 and 18 and the cylindrical surface of the tube 12.

When the inboard leg 20 of the channel shaped flange is bent in an outboard direction, the upstanding flange 16 within the channel shaped flange is also bent. Thus, a more pronounced hooking type of interlocking engagement is produced between the flanges 16 and 18.

The drive rollers 32, 34, 36 and 38 are preferably skewed or angled relative to the mandrel 26. The angularity of each roller preferably corresponds to the helical pitch angle of the coiled strip 14.

The drive rollers 32-38 are preferably driven at a substantially greater surface speed than the surface speed of the mandrel 26. In this way, the coiled strip 14 is caused to slide continuously around the mandrel 26 to a small extent, so that there is no possibility that the strip will adhere to the mandrel. Moreover, the over-speed driving of the rollers 32-38 tends to expand the coiled strip so that a loose sliding fit is produced between the strip and the mandrel 26.

As shown to best advantage in FIG. 6, the thin tapering wheel 60 is preferably angled to a considerable extent relative to the adjacent drive roller 38. In this way, the thin edge portion of the wheel 60 is enabled to enter the acutely angled groove or channel 64 between the partially bent flanges 16 and 18 and the cylindrical periphery of the tube 12.

While the wheel 60 could be driven, it is preferred to mount the wheel for free rotation so that it idles freely as it is driven by the rotating tube 12. The illustrated roller 60 is mounted for free rotation on a stationary holder or bracket 66.

Means are provided to flatten the partially bent flanges 16 and 18. The flattened flanges 16 and 18 form an interlocking helical seam or joint 68, as shown to best advantage in FIGS. 3, 5 and 6. In this case, the flanges 16 and 18 are flattened by an additional flattening roller 70, adapted to compress the flanges against the mandrel 26. The roller 70 is formed with a cylindrical flattening surface 72.

It is preferred to angle the flattening roller 70 at an even greater angle than that of the drive rollers 32-38. Thus. the roller 70 is skewed or angled relative to the 4 mandrel 26 at an angle substantially greater than the pitch angle of the helically coiled strip 14. This increased angling of the roller produces a wiping action between the roller and the partially bent flange 18, so that the roller flattens the flange with increased efficiency. Moreover, the roller 70 provides a propelling force, urging the finished tube 12 to travel along the mandrel 26.

The flattening roller 70 is preferably driven by the drive mechanism 28 through a driving connection 74. It is preferred to drive the flattening roller 70 at a surface speed substantially greater than the surface speed of the mandrel 26.

The flattened seam 68 extends helically around the finished tube 12 and is substantially rigid and fluid tight. However, the helical convolution 24 imparts flexibility to the finished tube 12.

It may be helpful to summarize the operation of the machine 10. The metal strip 14 is preformed by another machine or some other suitable means. The strip 14 is fed to the mandrel 26 at the required pitch angle. The strip 14 is directed between the mandrel 26 and the first drive roller 32 which presses the strip against the mandrel and propels the strip around the mandrel. The strip 14 is guided along its helical path by the helical guide surface 56 on the stationary annular guide 54.

The strip 14 is propelled successively between the mandrel 26 and the other drive rollers .34, 36 and 38. The coiled strip 14 rotates with the mandrel 26 but at a somewhat greater speed, due to the fact that the drive rollers 32-38 are driven at a greater surface speed than that of the mandrel 26. The strip 14 is coiled so that the channel shaped flange 18 is received over the upstanding flange 16, in an interlocking relation thereto.

When the channel shaped flange 18 reaches the drive roller 38, the flange is bent in an outboard direction by the frusto-conical bending surface 58 on the roller 38. The thin edge of the bending wheel 60 acts in opposition to the frusto-conical bending surface 58, so that the outboard leg 22 of the flange 18 is bent or tucked into the acutely angled groove 64 between the partially bent flange 18 and the cylindrical periphery of the tube 12.

Subsequently, the partially bent flange 18 passes between the mandrel 26 and the flattening roller 70, which exerts a heavy pressure so as to flatten the flanges 16 and 18 to form the flattened seam 68. The flattening roller 70 is driven at a greater surface speed than that of the mandrel 26 so as to assist in the movement of the tube 12 along the mandrel. Moreover, the flattening roller 70 is skewed or angled more sharply than the pitch angle of the helically coiled strip 14, to produce a wiping action between the flattening roller and the flanges 16 and 18. In this way, the flattening efliciency of the roller 70 is increased.

In the finished tube 12, as shown in FIG. 3, the flanges 16 and 18 are flattened to form the interlocking seam 68, which is rigid and substantially fluid tight. The desired flexibility is imparted to the tube by the helical convolution 24.

The tube making machine 10 is capable of operating I very efficiently and at a high speed, so that the cost of forming the tube is very low. Nevertheless, the helical seam in the tube is formed in a secure and rigid manner.

Various other modifications, alternative constructions and equivalents may be employed, as will be understood by those skilled in the art.

I claim:

1. A machine for making a metal tube from a metal strip having an upstanding longitudinal flange along one edge and a channel shaped flange along the other edge,

said machine comprising a rotatable mandrel,

first drive means for rotating said mandrel,

means including a plurality of drive rollers disposed adjacent said mandrel for engaging the strip and coiling it helically around said mandrel with the channel shaped flange of each coil interlocked with the up standing flange of the preceding coil,

said drive rollers being distributed at angular intervals around said mandrel,

each drive roller being disposed at an angle relative to said mandrel corresponding to the pitch angle of the helically coiled strip,

second drive means for rotating said drive rollers at a surface speed appreciably greater than the surface speed of said mandrel,

one of said drive rollers having a frusto-conical surface for engaging the inboard leg of said channel shaped flange and bending said inboard leg in an outboard direction,

a thin tapering disc-shaped wheel adjacent said frustoconical surface for engaging the outboard leg of said channel shaped flange in opposition to said frustoconical surface,

said thin tapering wheel being tapered in thickness between its center and its edge,

said tapering wheel being mounted with its axis angu-Iarly related to the axis of said one drive roller,

a flattening roller for engaging the angularly bent channel shaped flange and flattening such flange to rigidify the joint between the channel shaped flange and the upstanding flange,

said flattening roller being disposed with its axis at an acute angle to the axis of said mandrel,

ary guide disposed around said mandrel and having a 10 helical end surface for engaging and guiding the upstanding flange of said strip along a helical path.

References Cited UNITED STATES PATENTS 2,136,942 11/ 19 38 Freeze 7250 2,406,943 9/ 1946 Carter 7250 2,595,747 5/1952 Andersen 7250 3,122,115 2/ 1964 Siegwart 11354 FOREIGN PATENTS 144,302 7/1949 Australia 72-50 25 RICHARD J. HERBST, Primary Examiner 

